This application claims the priority of German Patent Document, filed Mar. 6, 1999, the disclosures of which is expressly incorporated by reference herein.
The invention relates to a subframe for a motor vehicle, particularly for a rear axle of a motor vehicle, having a chassis frame which can be fixed on the vehicle body, including cross members which are connected with side members, bearings for suspension links provided on the side members, and a transmission assembly arranged in the chassis frame between the side members and the cross members.
From German Patent Document DE 41 29 538 C2, a subframe is known which comprises side parts extending in the longitudinal direction of the vehicle and cross members arranged with respect to the side parts, which cross members are connected with one another. The side parts have bearings for suspension links of a wheel suspension and one cross member has a bearing for a rear axle differential gear.
It is an object of the invention to provide a torsion-resistant stable subframe for a motor vehicle which can be fastened as an assembly unit on the vehicle body with the wheel suspension, the brake module and possibly the transmission assembly on the vehicle body as a whole.
According to the invention, this object is achieved by providing a subframe of the above-noted type, wherein one side member structure of each side in each case has two members which are arranged one above the other and which have a through-opening for axle shafts of the transmission assembly between one another and converge approximately at end sides thereof and are connected with the cross members, the transmission assembly being connected by way of a three-point bearing with the cross members and side members, and with the axle shafts of the transmission assembly extending through the through-opening toward the wheel.
A subframe according to the invention is provided which has two side members which are arranged one above the other and have between one another a through-opening for fitting through axle shafts of a transmission assembly. The members of one side converge approximately at end sides thereof and are connected with the cross members, the transmission assembly being held by way of a three-point bearing at the cross members and the side members. The axle shafts of the assembly extend freely through the through-openings toward the wheel.
As the result, a subframe is advantageously formed which has a rigid high-strength connection for the bearing of the swivellable wheel suspensions and for a stable bearing of the rear axle differential gear.
The arrangement of two tube-shaped side members of one side can be adapted to the space requirements in the vehicle as well as to the conditions of the wheel suspension because, as the result of corresponding angled bendings, these side members can be partially situated at different spatial planes.
As a result, it becomes possible that one bottom side member, at a forward end side in relation to the driving direction, has in each case a forward bearing, and the additional upper side member has a rearward bearing at a rearward end side for the fastening to the vehicle structure. Furthermore, the bearings can be situated at different horizontal levels, the forward bearings being situated in a deeper plane than the rearward bearings. Because of the fact the side members each have angled bends at least in one horizontal and at least in one vertical plane, the through-openings as well as the bearing points for the wheel suspensions and the bearing points for the transmission assembly can be defined and disposed directly on the side members and cross members.
The through-openings for the axle shafts are formed in that at a forward free end in relation to the driving direction, the upper side member is bent at an angle with respect to the lower side member and is connected with its front-side end to the lower side member. Furthermore, the two rearward free end pieces are situated one above the other and are connected with one another along a common path. The space between the two side members is constructed approximately in the shape of a square, the axle shaft having sufficient clearance in this through-opening.
The tube-shaped side members are, for example, components formed by the application of internal high pressure so that the diameters of the tubes can be adapted to the space conditions and to the strength requirements.
The cross members each have a two-shell construction and consist of two assembled supporting profiles enclosing a hollow space, whereby the manufacturing of the members is simplified and a light-weight component is formed.
Particularly for the cross member which is situated in the front in the driving direction, two U-profiles or two hat-type profiles are used and, for the rearward cross members, two profiles are used, one profile being constructed as an angle profile and the other being constructed as a U-shaped profile.
According to the invention, for example, drawn cross members, cast cross members or cross members components formed by the application of internal high pressure are also contemplated.
The rearward cross member has an exterior recess in a center area for a portion of a spare wheel pan, whereby the member cross-section changes from the end-side square or rectangular cross-section to a central triangular cross-section.
On the upper and lower side members, bearing brackets are fastened for bearings of control arms of an upper suspension link, in the lower side member, additional bearing brackets being provided for bearings of an A-arm of a lower suspension link.
The rear axle differential gear or the transmission assembly is held in the chassis frame of the subframe by way of a three-point bearing, the rearward cross member preferably having two bearings and the forward cross-member preferably having one bearing.
So that, in a simple manner, the housing neck of the rear axle differential gear arranged between the cross-members can be guided toward the front, in relation to the driving direction, and can be disposed in a predetermined plane, the forward cross-member is provided with an approximately central receiving depression, whereby the two profiles forming the member have a correspondingly bent design, and a concave depression is obtained.
So that, in a simple manner and without additional brackets and reinforcements, the bearings can be arranged on the subframe for the fastening on the vehicle body, the free ends of the side members have a flat shape, so that two parallel spaced surfaces are obtained. The bearing will then be held in a semicircular front-side recess and will be fastened by way of a weld.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.